Hello,
1) Incase the Tape Drive/Autoloader is installed on a RAID controller. Please move this off to it's own standard SCSI controller for proper functionality with the device.
2) Make sure RSM (Removable Storage) service is stopped in the services applet.
We presume you have installed the latest driver.
3) The general recommended SCSI IDs for tape drives are 2,3,4,5.
IDs 0 & 1 should be reserved for bootable devices such as hard disks.Change the SCSI ID 6 to any other available ID.(if its assigned).The SCSI target ID 6 is reserved for automatic configuration of SCSI devices.
Once verified, Uninstall and re-install the veritas driver using this technote.
http://support.veritas.com/docs/243636
Thank You,
Shweta